Pipette tips are used in large quantities for a wide variety of applications related to liquid material handling, such as measuring, dispensing and aspirating of the liquids. Pipette tips are often used in conjunction with hand held pipettors, such as mechanical or electrical pipettors, that have distal nozzles that are configured to be releasably engaged with a proximal port or opening of a pipette tip in a sealed relationship. The pipettor may then be used to apply a vacuum or otherwise decrease the pressure in the interior volume of the pipette tip in order to aspirate liquid into the pipette tip for transfer to another location. For some applications a single pipettor may be used, however, for some applications, particularly automated or robotic applications, pipettors or manifolds having multiple distal nozzles may be used to engage multiple pipettor tips disposed in a loading plate or block simultaneously.
For such configurations, after the pipette tips are seated onto the nozzles and removed from the loading block, a new set of pipette tips must be provided for the next cycle of liquid handling. Typically, a new set of pipette tips are taken from a package in a storage plate and loading block in a regularly spaced array and positioned for seating with the distal nozzles of the manifold. Because of the difficulty of manually handling large numbers of pipette tips due to the time consuming nature of such handling as well as the risk of contamination, pipette tips are generally pre-packaged in regularly spaced arrays spaced in pre-determined spacing to match the spacing of the array of distal nozzles. The pipette tips may be transferred from the packaging in a loading plate that is part of the packaging but may also include an entire loading plate and loading block in order to maintain the array configuration during handling and transfer to a location for seating to the manifold or pipettor.
For such multiple pipette tip arrays, because each pipette tip may require a significant amount of axial force between the respective nozzle and proximal opening of the pipette tip in order to be properly seated, the cumulative force required to seat an array of pipette tips may be quite high. For example, a 96 tip manifold may exert about 75 pounds to about 250 pounds of force on a loading block having a 96 tip array. Because of the amount of force generated, the loading block that supports the loading plate must be structurally strong and able to withstand the cumulative axial force without significant deformation. To be this strong, the block requires a significant amount of mass of material which is typically a polymer. Once the distal nozzles of the manifold have engaged and seated the pipette tips and withdrawn them from the loading plate and block, the loading block and plate are disposed of and replaced with a new loading block and plate that is full of new pipette tips. As a result, a user performing a high volume of such liquid handling cycles will be disposing of a large volume of loading blocks and plates which generates a large volume of polymer waste which may be environmentally unsound in many instances.
For embodiments of pipette tip arrays that transfer in a loading plate without the loading block, the loading tray is lifted or moved from the packaging, as necessary, and positioned over a loading block. After each seating of an array of pipette tips, the loading plate must be removed or the z-axis position of the top of the plate will change with the addition of each new loading plate from a new package of pipette tips.